1. Field of the Invention
The present invention generally relates to an antenna unit and, more particularly, to an antenna unit for use in a mobile communication system and in a local area network (LAN).
2. Description of the Related Art
FIG. 12 is a side view of a conventional tip antenna. The tip antenna 50 consists of: a rectangular-prism-like insulator 51 formed by stacking up insulating layers (not shown) made of powdery insulating materials such as alumina and steatite; a conductor 52 which is made of silver or silver-palladium alloy or the like and is formed like a coil in the insulator 51; a magnetic element 53 which is made of magnetic powder such as ferric powder and is formed inside the insulator 51 and the coil-like conductor 52; external connecting terminals 54a and 54b which are made to adhere and are baked in such a manner as to stick to the lead-out end (not shown) of the conductor 52 after the firing of the insulator 51. Namely, the tip antenna 50 is configured so that the coil-like conductor 52 is wound around the magnetic element 53 and a space therearound is filled with the insulator 51. Further, by using a material having a low relative permeability as the magnetic element 53, a tip antenna 50 which has a low resonance frequency of tens to hundreds MHz can be produced.
However, the aforementioned conventional tip antenna has a problem in that when produced as a small-sized antenna having a low resonance frequency, the gain and bandwidth thereof are degraded.
The present invention is accomplished to solve such a problem of the conventional tip antenna.
Accordingly, an object of the present invention is to provide an antenna unit which has a high gain and a wide bandwidth at a low resonance frequency.